OMG Susanne, how funny that you have a GSD too. Mine is also female (although just under 6 yrs old---but I just rescued her about 7 months ago). Even more ironic is that your dog sounds just like mine. Dakota is the perfect affectionate angel with my husband & I and the weekly yard helper, but NO ONE else can come in or near the house or me. She is very sensitive too.

I got her for companionship and to help me with pain mgmt and to keep me moving. She is nuts about fetch with balls and frisbees so we play 4-5 times a day (very short sessions though). It's great for me to get out with her and walk her. Thankfully she is perfect on the leash so I can manage her walking around our large property.

We have trained her for a couple service jobs. I have a lot of falls and I'm by myself during the day. She can now find and bring me the phone from any room in the house. Of course she doesn't like strangers, so it was pointless to train her to bring me the phone in an emergency if she won't let EMT's in the house to help me. So we have also trained her to go to her crate and pull on a sock attached to a rope that closes the door. We are putting a self locking latch so it will lock. She has mastered the phone but we've only worked on the door closing for about 3 weeks. She's already good at closing the door, but we are mastering the task from different rooms in the house and right after she brings me the phone. She's super smart and my husband is more at ease leaving me home alone now that she's with me.